Disk brake for railway vehicles



United States Patent 2,184,683 12/1939 Shuman 3,034,599 5/1962 GaenssleInventors Appl. No. Filed Patented Priority DISK BRAKE FOR RAILWAYVEHICLES 9 Claims, 7 Drawing Figs.

U.S. Cl. 188/59, 188/73, 188/106, 188/196 Int. Cl. B6lh 5/00; F16d65/14, F16d 65/52 Field of Search 188/59,

72W, 73, 73C, 196RR, PRR, 1061 79565 References Cited UNITED STATESPATENTS l88/79.5(GE) 188/59 Primary Examiner-George E. A. HalvosaAttomeyEdmund M. Jaskiewicz ABSTRACT: A U-shaped yoke straddles theperipheral edge of a brake disc with one leg of the yoke carrying abrake shoe on its inner face while in the other leg there is slidablymounted a rod which is movable axially toward and away from the brakedisc. The end of the rod adjacent the brake disc is provided with abrake shoe and the other endpf the rod has an inclined surface which isparallel to a second inclined surface on a wedge member carried on theend of a piston rod extending from a brake actuating cylinder mounted onthe yoke. Roller means are interposed between the parallel inclinedsurfaces so that actuation of the brake cylinder piston rod istranslated into axial movement of the brake shoe rod to apply the brakeshoe into frictional engagement with the brake disc. The rod is providedwith an automatically operable arrangement to compensate for brake shoewear.

PATENTED 05m slgm SHUT l H 5 FIG. 7

FIG

HAN; PC 15 21 LAWRENCE J LUNGHAMER AITOHN Y SHEET U E PATIENTEDIDEB 1519m FIG. 6

INYF NV/FC POLLIHCU J LUNGHAMEJ" HANS LAWRENCE lllil pmgmgunmsmm SHEET 5BF 5 35471229 FIG.7

DISK BRAKE FOR RAILWAY VEHICLES The present invention relates to a discbrake for railway vehicles, more particularly to the structure foractuating such a disc brake where the brake shoes are-mounted on thelegs of a yoke straddling the peripheral edge of a brake disc Discbrakes as generally used on railway vehicles include one or more brakeshoes which are moved into braking engagement with one or both sides ofa brake disc mounted on the wheel or axle of a railway vehicle. Manyfonns of actuating mechanisms for such brakes have been devised. In onesuch structure a pair of resilient brake levers are moved into brak' ingengagement with opposed faces of a brake disc somewhat in the manner oftongs. A fluid pressure-actuating cylinder moves wedge-shaped pressuremember between the free ends of the brake levers to move the brake shoescarried by the other ends of the brake levers into frictional engagementwith the brake disc. The free ends of the'brake levers are positionedgenerally radially forwardly of the brake disc and it is thus necessaryfor the brake levers to be mounted on the vehicle frame forwardly of thebrake disc at a substantial distance from the vehicle wheel axle. Thisarrangement is disadvantageous since a necessary amount of space toaccommodate the mechanism forwardly of the brake disc is often notavailable. I

It has therefore been proposed to mount the actuating cylinder on thevehicle frame laterally of the vehicle wheels and to move the wedgelikepressure member between the free ends of the pair of brake levers bymeans of a lever mounted radially in front of the brake disc. However,this arrangement also required a relatively large amount of space toaccommodate a rather elaborate system of braking linkages includingseveral straight and angular levers with their requisite pivotalconnections.

In another form of brake disc there is provided a U-shaped yoke whichstraddles the peripheral edge of a brake disc with one leg of the yokecarrying on its inner face a brake shoe with the other leg slidablysupporting an axially movable rod having a brake shoe on its endadjacent the brake disc The actuation of the rod is accomplished bymeans of an angular lever that is pivotally connected on the yoke and isconnected to the otherv or rear end of the rod. In this arrangement thebraking force must be transmitted through this pivotally mounted leverand the several pivotal connections are readily susceptible toconsiderable wear and to malfunctioning. Because only a limited space isavailable for hearing connections; the distances from the leverconnection on the yoke to the rod upon which force is transmitted mustbe greater than a certain predetermined length if the desiredtranslation ratio is to be maintained. This would require a relativelylong lever arm to be connected to the actuating cylinder which in turnwould have to be attached to the vehicle frame by special mountingbrackets. Further, the actuating cylinder would have to be located atconsiderable distance from the brake.

It was therefore proposed that in such a disc brake employ ing aU-shaped yoke the actuating fluid pressure be applied between a fixedwall in the yoke and a diaphragm which actuates a piston movably mountedin the yoke and connected to a brake shoe. However, this system had thedisadvantage that it was impossible to provide any translation of thebraking force. A further disadvantage of disc brakes using levers as atranslating mechanism is that these mechanisms are not symmetrical andthat structurally different brake structures are necessary for the rightand left side disc brakes.

It is therefore the principal object of the present invention to providea novel and improved disc brake for railway vehicles.

It is another object of the present invention to provide a railwayvehicle disc brake wherein a U-shaped yoke straddles the peripheral edgeof the brake disc with the brake shoes being operated by a fluidpressure-actuating cylinder mounted on the yoke.

It is a further object of the present invention to provide a disc brakefor railway vehicles wherein the force exerted by an actuating cylindermay be translated to the brake shoes without levers.

It is still another object of the present invention to provide anextremely compact unitary brake disc unit for railway vehicles which canbe used on either side of a brake disc without modification.

According to the present invention, the disc brake for railway vehiclesmay comprise a U-shaped yoke having two legs straddling the peripheraledge of a brake disc. A brake shoe is mounted on the inner face of oneleg and the other leg slidably carries a rod which is axially movabletoward and away from the brake disc with such movement beingsubstantially perpendicular to the disc. A second brake shoe is carriedon the end of the rod adjacent the brake disc.A brake cylinder iscarried by the yoke and has :in actuating rod extending therefrom with awedge member being carried on the end of the actuating rod. The wedgemember has an inclined surface which is parallel to a second inclinedsurface carried on the other end of the rod. Roller means are interposedbetween the parallel inclined surfaces so that actuation of the brakecylinder will move the actuating rod and the movement of the actuatingrod will be translated by means of the inclined surfaces and rollermeans to the brake shoe rod.

The brake shoe rod is provided with an automatically operable mechanismto compensate for any wear in the brake shoes resulting from repeatedbraking.

Other objects and advantages of the present invention will be apparentupon reference to the accompanying description when taken in conjunctionwith the following drawings wherein;

FIG. 1 is a schematic representation of the disc brake unit according tothe present invention;

FIG. 2 is a sectional view taken along the longitudinal axis of thebrake shoe rod of a disc brake according to the present inventionprovided with an automatic mechanism to compensate for brake shoe wear;

FIG. 3 is a sectional view taken along the line Ill-III of FIG. 2;

FIG. 4 is a sectional view taken along the line lV-IV of FIG.

FIG. 5 is a side view of a portion of a disc brake unit according to thepresent invention utilizing a manually operable brake lever;

FIG. 6 is a front view of the structure illustrated in FIG. 5; and

FIG. 7 is a sectional view taken along the line VII-VII of FIG. 6.

Proceeding next to the drawings wherein like reference symbols indicatethe same parts throughout the various views a specific embodiment andmodifications of the present invention will be described in detail.

In FIG. 1, there is indicated at I a brake disc which is fixedly mountedon an axle or may be mounted to the hub of a wheel of one of the twowheels on an axle. The brake disc is generally provided with aventilating structure such as cooling ribs. prake discs may also bemounted on opposite sides of a whee On opposed sides of the brake discthere are mounted brake shoes or friction means 2 and 3. Brake shoe 2 ismounted on the inner face of a leg 5 of a U-shaped yoke 4 having anotherleg 6 provided with a chamber 7. Slidably carried within chamber 7 is apush rod 8 that is movable axially in a direction which is substantiallyperpendicular to the brake disc 1. The brake shoe 3 is mounted on theforward end of push rod 8 with the rear end of the rod being attached toa wedge member having an inclined pressure surface 9.

A wedge member 12 is positioned between the inclined pressure surface 9and a fixed wall of leg 6. The wedge member 12 is mounted on the end ofa piston rod 13 of a fluid pressure brake actuating cylinder 14 that iscarried by the yoke 4. The wedge member 12 is provided with an inclinedface 19 whose height increases in the direction of the brake cylinder 14with the inclined surface being substantially parall el to the inclinedpressure surface 9. The opposite face of the w,'edge member 20 isparallel to the piston rod 13. A roller i'sinterposed between theparallel inclined surfaces 9 and 19 and, similarly, a roller 11 ispositioned between the opposite surface of the wedge member and thefixed rear wall of leg 6 of the yoke. Instead of the rollers, ballbearings mounted in a suitable cage may also be used.

, Within chamber 7 there is positioned a spring 15 to urge the inclinedpressure surface 9 through roller 10 against the inclined wedge surface19.

L The U-shaped yoke 4 together with the brake cylinder 14 which may beintegral therewith is supported from the vehicle frame by any suitablemounting attachment such as by means of hangers attached to brake shoes2 and 3.

"The actuating cylinder 14 is actuated by a suitable fluid pressurewhich may be either pneumatic or hydraulic. When fluid under pressure isintroduced into the actuating cylinder 14; wedge member 12 will be movedby piston rod 13 in the direction of the arrow 16. This movement of thepiston rod will be translated through the inclined parallel surfaces 9and l9 and the roller to the push rod 8 so that this rod will be movedin the direction of the arrow 17 toward the brake disc 1 and against theforce of return spring 15. Brake shoe 3 will thus be moved from adisengaged or released position slightly spaced from brake disc 1 intothe engaged or braking position with its friction surface engaging thefriction surface of brake disc 1. Further movement of wedge member 12 inthe direction of the arrow 17 will caUse the U-shaped yoke to be shiftedin the direction of arrow 18 so that the brake shoe 2 viill'also bemoved from its disengaged or released position into the braking positionagainst brake disc 1.

.Upon release of the brakes by exhausting pressure fluid from brakecylinder 14; wedge member 12 will be moved in a direction opposite tothat indicated by arrow 16 and under the action of spring 21 will bereturned to its original disengaged position. At the same time, returnspring 15 will move the pressure surface 9 in a direction opposite tothat indicated by arrow 17 so that brake shoe 3 is disengaged from brakedisc 1. Because of the pivotal suspension of the U-shaped yoke 4 brakeshoe 2 will also return to its original or disengaged position.

Proceeding next to FIGS. 2--4 there is illustrated in detail a preferredconstruction of the right-hand half of the U-shaped yoke 4 which isshown schematically in FIG. i. In F IG. 2, the yoke is indicated at 22and has an l-shaped cross section and has. only a small space in aradial direction from the peripheral edge of brake disc 23. The yoke22'is thus substantially parallel'to the rotational axis of the brakedisc 23. As viewed in FIG. 2, the right-hand portion of yoke 22 has anS-shaped curved yoke portion 24 in the direction of the rotary axis ofbrake disc and at its end 25 carries a cylindrical sleeve 26 whichextends in an axial direction toward the brake disc. Also atfend 25 ofthe yoke portion 24 there is rigidly mounted an a'ctuating'cylinder 27only a portion of which is indicated. Through an opening 29 there isslidably positioned a piston rod 30 extending outwardly from actuatingcylinder 27 into the} rearward portion of the cylindrical sleeve 26. Awedge shaped pressure member 31 is mounted on the free end of piston rod30 and is provided with a surface 32 which is parallellto the axis ofpiston rod 30 and on its opposite face with an inclined surface 33 whichrises in the direction of actuating cylinder 27. Both surfaces 32 and 33are provided with longit udinal grooves 34 and 35 respectively in whichthere are seated ball bearings 39 and both of which are retained in acage indicated at 36. Ball 39 is also supported in a longitudin'allyextending groove 37 formed in a pressure plate 38 which is rigidlysecured at the rear end of cylindrical sleeve 26?! T 'lhe other ball 40is similarly supported in a longitudinal groove 42 formed in an inclinedsurface 43 of a pressure member 44. The inclined surfaces 33 and 43 withball 40 interposed therebetween and the surfaces 32 and 33 with the ball39 interposed therebetween will always remain parallel to each other.

The pressure member 4% is ring-shaped and is axially movable within thecylindrical sleeve 26. On the outer peripheral surface of pressuremember 44 there is a longitudinally extending groove 45 which receives apin 46 fixedly mounted in sleeve 26. in the face of the pressure memberaway from inclined surface 43 there is an axial bcreM which receives arearward tubular extension 48 of a nut 49 provided with internal screwthreads at 50 only in its forward portion and which is axially movablewithin the cylindrical sleeve 26. A spindle or rod 50 is screwed intothe threaded portion 50' of nut 49' and has its forward end 51projecting outwardly of the cylindrical sleeve 26. On the rod end 51there ismounted a brake head 52 having a brake shoe 53 thereon.

The end of tubular extension 48 of nut 49 is indicated at 55 and engagesbottom surface 56 of pressure member axial bore 47. Between theextension 43 from nut 49 and the pressure member 44 there is provided aunidirectional coupling 90 (shown in FIG. 3) which includes aspring-biased ball seated in an inclined groove in such a manner thatrelative rotation between pressure member 44 and the nut 49 can occur inonly one direction. An annular spring 62 is positioned in front of thepressure member 4d and prevents the ball and spring of the coupling 90from dropping out.

Nut 49 has a rearwardly facing shoulder 57 upon which there are providedratchet teeth 58. An axially movable ring 59 is rotatably mounted on thenut extension 48 so as to be positioned between the pressure member 64and the rearwardly facing shoulder 57 of the nut. On the forward face 60of ring 59 there are provided ratchet teeth 61 which mesh with ratchetteeth 58 on the nut 49. Annular spring 62 which is positioned betweenthe pressure member 44 and the ring 59 urges ring ratchet teeth 61 intomeshing engagement with nut ratchet teeth 58.

On the outer peripheral surface of the ring 59 there are formed twodiametrically opposed inclined grooves 86 and 87 as may be seen in FIG.4. These grooves receive the inner ends of pins 88 and 89 that arescrewed into the wall cylindrical sleeve 26 as shown in FIG. 4-. Thediameters of pins 88 and 89 are considerably less that the width of thegrooves 86 and 87 so that ring 59 is free for limited axial movement butwhen moved over a longer axial distance will be rotated by theinteraction of the pins 88 and 89 with their respective grooves 86 and87.

The forward end of nut 49 is provided with another tubular extension 63around which there is formed a shoulder 64 against which is seated athrust bearing 67 having balls 68. A compression spring 66 is interposedbetween the ball bearing 67 and a washer retained in position by meansof a split ring 70 seated in an annular groove 69 formed in the forwardend of cylindrical sleeve 26. Forwardly of the cylindrical sleeve 26 ahand wheel 71 is fixedly secured to the spindle or rod 50. The handwheel is provided with a rearwardly extending flange 72 which encirclesthe forward end of sleeve 26. The junction between the forward end ofcylindrical sleeve 26 and the hand wheel flange 72 is enclosed by aprotective flexible bellows 74' one end of which is held on the outersurface of sleeve 26 by a ring 73 and its other end similarly secured toa ring 74 rotatably seated on the outer periphery of flange 72.

The brake head 52 is mounted by ribs or fins 75 to a cylindrical cap 76which fits over the front end 51 of rod 543. 76 is provided with athreaded hole 79 in which there is screwed a nipple 80 having an axialbore M in which there is slidably mounted a detent or latching bolt 77having a pull ring 78. At

the forward end of latching bolt 77 there is formed a shoulder againstwhich a force is exerted by a spring 84 seated in bore 81. The inner endof bolt 77 is engagable with any one of four recesses 33'circumferentially spaced around the periphery of rod end portion 51.The cap '76 is rotatably supported on the end of rod 59 but retainedagainst axial movement by means of a bolt 96 extending transverselythrough the cap 76 and received in a peripheral groove formed in the rod53. i

The structure as described above functions to automatically compensatefor wear in the brake shoe 53. Regardless of wear in the brake shoe 53resulting from repeated braking operations the brake shoe will bepositioned at the same distance from the brake disc when in thedisengaged position. This brake shoe resetting or compensating mechanismwill operate as follows:

Actuation of braking cylinder 27 will cause piston rod 30 to move in thedirection of arrow 91. By the interaction of ball 40 between theinclined surfaces 33 and 43 pressure member 44 will be moved axially inthe direction of arrow 92. The transla tion ratio of the movement ofpressure piece 44 with respect to piston rod 30 will depend on the angleof inclination of wedge member surface 33. Axial movement of pressuremember 44 will then move nut 49 with its rod 50 and ring 59 acorresponding distance. Pressure spring 66 will be compressed throughthe same axialdistance. For overcoming the-necessary play between brakeshoe 53 and brake disc 23, the ring 59 is first moved in the directionof arrow 92 a distance less than the normal braking movement until theends of pins 88 and 89 engage the walls of guide grooves 86 and 87. If,after this movement, the brake shoes are still not in braking positionagainst the brake disc then further axial movement of pressure piece 49in the direction of the arrow 92 will cause rotation of ring 59 by theinteraction of the inclined guide grooves 86 and 87 with theirrespective pins 88 and 89. As ring 59 rotates, its ratchet teeth 61 willmove over the ratchet teeth 58 of nut 49 corresponding to the resettingof the brake shoes. During this time, coupling 90 retains nut 49 againstrotation in this direction and as annular spring 62 compresses and ring59 moves axially away from nut 49 the ratchet teeth 58 and 61 will bedisengaged.

When the brake is disengaged, piston rod 30 will be moved in a directionopposite to arrow 91 and spindle 50 will be moved back in the axialdirection opposite to arrow 92 under the action of the compressed spring66. The axial movement of spindle 50 will be through a distance equal tothe free play of the brake shoe until the ends of pins 88 and 89 engagethe opposite sides of guide grooves 86 and 87. Ring 59 will then berotated back to the previously selected resetting distance whereby theratchet teeth will again mesh so that nut 49 will rotate with ring 59while the coupling 90 is disengaged during rotation in this direction.In this manner, the nut 49 is rotated with respect to the spindle 50through a resetting distance which was automatically selected by therotation of ring 59 at the beginning of the braking action. The spindle50 will then be screwed outwardly with respect to nut 49 a sufficientdistance so as to automatically maintain a predetermined amount of playof the brake shoe independently of the application of the brakes. Thusthe play or distance the brake shoe must move before braking actioncommences will always be the same.

When the brake shoes are replaced the desired play between the brakeshoe and brake disc can be adjusted by use of hand wheel 71. Thelatching bolt 77 is disengaged from one of the recesses 83 and thethreaded spindle then adjusted within nut 49 by rotation of the handwheel 71 to set the desired distance between the brake shoe and brakedisc. After this adjustment is completed, the latch bolt '77 ispermitted to engage one of the recesses 83 under the action of spring84.

Proceeding next to FIGS. 5-7, there is'shown a modification of the discbrake of the present invention wherein the left side of the U-shapedyoke as viewed in. FIG. 1 is modified to accommodate a manually operatedbraking lever. The yoke is indicated at 101 with its left leg 102 beingforked as best shown in FIG. 6. The upper ends of the fork legs 102 arepro-.

vided with recesses 104 and 105 opening toward brake disc 23 to receivea transverse bolt 103. Between the bearing recesses 104 and 105, bolt103 carries a knuckle 106 to which is attached a manually operated brakelever 107 which is pivotally The forked legs 102 are provided withopenings 113 and 114 and the brake lever 107 is provided with an opening115 with a spring bar 116 extending through these openings. The springbar 116 urges brake lever 107 in a counterclockwise direction as seen inFIG. 5 to maintain transverse bolt 103 seated within the bearingrecesses 104 and 1.05. When the lower end of brake lever 107 is moved tothe left as viewed in FIG. 5 by manual actuation of the brake linkagemechanism, the brake head 111 and the brake shoe will be moved to theright into braking engagement with brake disc 23. At the same time, bolt103 will be moved slightly outwardly with respect to recesses 104 and105 against the force of spring bar 116 and mounted on yoke 103 at 108.At both sides of the bearing yoke 101 will be moved to the left by thepivot bearing 108.

It is apparent that the braking unit illustrated in FIG. 1 isbilaterally symmetrical and can be used as a left-hand or righthandbraking unit. In FIG. 1, the braking unit is shown in the right-handposition and to convert the unit into a left hand unit it is onlynecessary to turn yoke 4 around in the opposite direction and totranspose the suspension members for connecting similarly shaped brakeshoes 2 and 3 to the vehicle frame.

Thus it can be seen that the present invention has disclosed a discbrake which is compact in structure and is bilaterally symmetrical.Further the disc-braking unit disclosed herein occupies a minimum ofspace underneath the vehicle with a major portion of the brake unitbeing positioned laterally of the brake disc. The braking unit may beprovided with an automatically operable mechanism to compensate for wearin the brake shoes so that the free play between the brake shoes in thedisengaged position and the brake disc remains'constant after repeatedbraking operations. The left-hand end of the yoke as viewed in FIG. 1may also be modified to accommodate a manually operable braking lever. i

It will be understood that this invention is subject to modification inorder to adapt it to different uses and conditions and, accordingly, itis desired to comprehend such modification within this invention as mayfall within the scope of the appended claims.

We claim:

1. In a disc brake for railway vehicles, a U-shaped yoke having two legsstraddling the peripheral edge of a brake disc, a brake shoe on theinner face of one leg, a push rod slidably carried by the other leg ofsaid yoke and axially moveable toward and away from said brake disc, asecond brake shoe on the end of said push rod adjacent said brake 'disc,means carried by and acting upon said push rod for automaticallycompensating for brake shoe wear, a brake cylinder on said yoke andhaving a piston rod extending therefrom, a wedge member on said pistonrod and having an inclined surface and a second surface opposedtherefrom, an inclined surface on the other end of said push rod andparallel to said wedge member inclined surface, and roller means betweensaid inclined surfaces and between said wedge member opposed surface andthe other leg of the yoke whereby actuation of said brake cylinder willmove said piston rod and the movement of the piston rod will betranslated through said inclined surfaces and roller means to the brakeshoe push rod.

2. In a disc brake for railway vehicles as claimed in claim 1 with saidwedge member surface opposed from its inclined surface being parallel tosaid piston rod.

3. In a disc brake for railway vehicles as claimed in claim 1 with saidyoke one leg being bifurcated and having recesses in the bifurcated endsopening toward the brake disc a bolt seated within said recesses withthe brake shoe being mounted .upon said bolt, and a manually operatedbraking lever pivotally mounted on the yoke and having its upper endpivotally connected to said bolt.

4. In a disc brake for railway vehicles as claimed in claim 1 with saidpush rod being threaded, a nutthreaded upon said push rod and having atubular extension surrounding said rod, there being ratchet teeth onsaid nut surrounding said extension, a ring rotatably mounted on saidnut tubular extension and having ratchet teeth thereon meshing with saidnut ratchet teeth so that said ring is rotatable in one direction withrespect m said nut, there being inclined guide grooves in the peripheralsurface of said ring, and stationary pins projecting into said guidegrooves and loosely received therein so that said ring is axiallymoveable a distance substantially equal to the distance moved by thebrake shoe before engaging the brake disc, said ring being rotatable inone direction with respect to said nut a predetermined distance uponactuation of the brake and rotatable in the opposite direction togetherwith the nut when the brake is released.

'5. In a disc brake for railway vehicles as claimed in claim 4 andcomprising unidirectional slip clutch means engaging said nut to preventrotation of said nut in a direction to unscrew the nut with respect tosaid push rod.

6. In a disc brake for railway vehicles as claimed in claim 4 andcomprising a hand wheel mounted on said rod for rotating manually saidpush rod.

7. In a disc brake for railway vehicles as claimed in claim 4 with saidsecond brake shoe being rotatably mounted on the end of said push rod. J

8. In a disc brake for railway vehicles as claimed in claim 7 with saidsecond brake shoe having a cap rotatably mounted on the end of said pushrod, and selectively operable detent means on said cap engageable withsaid push rod for nonrotatably retaining said cap thereon in apredetermined position.

9. In a disc brake for railway vehicles as claimed in claim 8 andcomprising means on said cap for retaining said cap against axialmovement on said rod while permitting rotary movement thereon. I

